Fescue grass presents a unique challenge because it exists both as a desirable, drought-tolerant turf and as a persistent, coarse weed. When it appears as a thick, wide-bladed clump within a finer lawn, its aggressive nature makes it difficult to eliminate. Complete removal requires a targeted approach, using either non-chemical methods that rely on physical suppression or the strategic use of highly effective herbicides. This article outlines the specific methods that kill fescue grass entirely, allowing for successful lawn renovation or spot repair.
Understanding the Fescue Goal
The method chosen for fescue eradication depends entirely on the scale of the problem: isolated clumps versus an entire lawn. Tall fescue often appears as individual, coarse, bunch-type plants that stand out visibly from finer turf like Kentucky bluegrass or fine fescue blends, often due to accidental seed contamination.
When the issue is limited to isolated clumps, the goal is targeted spot treatment to eliminate the weed without damaging the surrounding desirable grass. Conversely, if the majority of the lawn is an unwanted fescue variety or the infestation is widespread, a full lawn renovation is the most practical goal. Identifying the scope of the infestation dictates whether localized manual removal or a broad-scale chemical application is necessary.
Non-Chemical Removal Techniques
For those seeking to avoid synthetic chemicals, fescue can be killed using physical removal methods, though they require patience. Manual removal is best suited for isolated clumps and involves digging out the individual plant. It is important to remove the entire root crown, typically by cutting at least two inches into the soil with a spade, as any remaining root fragments can regrow.
For large areas, solarization is an effective method that uses heat and moisture to kill the grass. The process begins by mowing the area short and watering it deeply to moisten the soil. A sheet of clear plastic, preferably 2 to 6 millimeters thick, is then laid over the area and secured tightly around the edges to trap heat. The clear plastic allows solar energy to penetrate and raise the soil temperature to lethal levels, often exceeding 140 degrees Fahrenheit near the surface. This method requires six to eight weeks during the hottest part of the year to be fully effective.
Smothering, or sheet mulching, is a slower but equally chemical-free option. This method involves covering the mowed fescue with a light-blocking material, such as overlapping layers of cardboard or black plastic sheeting. This is then covered with a thick layer of mulch or compost. By completely blocking sunlight, the fescue cannot photosynthesize and eventually dies, decomposing underneath the layers. This process typically takes several months, making it suitable for areas where immediate replanting is not necessary.
Non-Selective Herbicide Use
The fastest and most reliable method for complete fescue eradication is the use of a non-selective herbicide. Glyphosate is the industry standard because it is a systemic herbicide that translocates from the leaves down to the roots, killing the entire plant. Selective herbicides are ineffective for fescue because they cannot distinguish between fescue and other desirable turf grasses.
For maximum effectiveness, the fescue must be actively growing when the herbicide is applied. If the grass is stressed by drought or excessive heat, it will not properly absorb and move the chemical throughout its system. Applying the product when the grass is 6 to 12 inches tall allows for optimal leaf surface area for absorption. The addition of a non-ionic surfactant can also improve the penetration of the herbicide into the waxy fescue leaves.
For a full lawn renovation, apply the product evenly across the entire area, following the label’s concentration instructions. Clumps can be spot-treated using a pump sprayer, shielding desirable grass with a barrier like cardboard to prevent drift. Fescue is tough, so a second application may be necessary after 10 to 14 days if green tissue remains. After application, the treated area must be left undisturbed for at least 48 hours to allow the chemical to fully absorb and translocate.
Safety precautions are mandatory when handling non-selective herbicides. This includes wearing personal protective equipment such as gloves, long sleeves, and eye protection. Avoid application on windy days to prevent the spray from drifting onto non-target plants. Pets and children should be kept away from the treated area until the spray has completely dried, typically a few hours after application.
Post-Eradication Cleanup and Soil Preparation
Once the fescue has turned completely brown, indicating a successful kill, the next phase is preparing the soil for new growth. The first step involves removing the dead plant material, which is now a dense layer of thatch. This debris should be vigorously raked, dethatched, or scalped with a mower set to its lowest height to expose the soil underneath, ensuring newly planted seed makes solid contact with the soil for germination.
If glyphosate was used, the waiting period before reseeding is minimal because the chemical rapidly binds to soil particles and becomes inactive. Although some products allow same-day seeding, waiting 7 to 14 days is a safer measure, especially after a heavy application. This delay ensures the systemic herbicide has fully translocated and is not accidentally absorbed by the new seedlings.
Before planting, the exposed soil should be prepared to create a fine, firm seedbed. Light tilling or aeration to a depth of half an inch to one inch helps break up the surface and improve drainage. Incorporating a thin layer of compost or a starter fertilizer can amend the soil and provide nutrients for the new grass. The soil should be firm enough that a footprint leaves only a slight indentation, which promotes good seed-to-soil contact and supports healthy root establishment.